It is sometimes argued that “race is just skin deep”. This diagram from a 2011 study shows how much three populations (from Africa, East Asia, and Europe) differ genetically from one another (according to the genetic measure used) and regarding gene groups with different functions. Red lines (additions to the original image) mark gene groups stated to be involved in pigmentation, hair development, and skeletal development (physical appearance). There are numerous other gene groups, including many involved in the nervous system or potentially involved in the nervous system (including the brain).1)

Races are natural divisions within a species, ultimately based on genetic similarity and genetic ancestry similarity.

Without modifier the term usually refers to human races.

Understanding genetic race differences has been seen as fundamental for understanding differences and interactions between human groups.

Ethnicity, nation, and race

History of the race concept

Early history

, circa 13th century BC.]]

Many non-Europeans made early distinctions between different groups of humans, stated different physical and mental characteristics of the different groups, and expressed views which today would be considered racism. Examples include views from Ancient Egypt, China, India, and Islamic and Jewish sources. Prehistoric paintings have been seen as evidence for that group distinctions were made also in prehistory.<ref name=reality>Vincent Sarich och Frank Miele. Race: The Reality of Human Differences. 2004. Westview Press.</ref><ref name=R2000>J. Philippe Rushton. Race, Evolution, and Behavior: A Life History Perspective. 1997. Transaction Publishers.</ref><ref>The Talmudic Roots of Jewish Supremacism by Dr. David Duke http://davidduke.com/the-roots-of-jewish-supremacism/</ref>

However, these ancient race classifications were limited by the lack of knowledge of many geographical areas and many human populations at this time.

Also in pre-modern Europe there were such views, although the focus was on groups that may today be classified as “peoples” or minor races rather than the major races (several of which were completely or largely unknown to Europeans at this time). Thus, “In classical and Medieval literature, the major term in ethnographic descriptions was gens—a Latin word that is usually translated as “people” or “nation.” Significantly, gens connotes a common ancestry or stock (hence its etymological link with genero, to beget or produce), reflecting an ancient way of understanding a nation not as a social or political unit, but as a group of people linked by origin. Gens was therefore close in meaning to “race,” understood in the traditional sense of “lineage” or “extraction.””<ref>Hudson, Nicholas. (1996). “From ‘Nation’ to ‘Race’: The Origin of Racial Classification in Eighteenth-Century Thought,” Eighteenth-Century Studies. 29. Spring. 248.</ref>

A politically correct view is that in the pre-modern period in Europe, the observed group differences was explained as due only to environmental factors. This would make hereditary race characteristics and racism recent European social constructs. This has been criticized by arguing that (as noted above) such not politically correct views on race existed in early non-European cultures. Furthermore, while the theory of evolution and natural selection did not exist before Darwin, it is argued that already in European Antiquity, there existed theories of soft inheritance (which refers to theories such as Lamarckism were the environment directly changes the hereditary material, instead of indirectly changing it, such as through natural selection). “In summary, the heredity of acquired characters is a concept generally accepted in Greece and Rome and explicitly formulated by several authors. It is found in several Hippocratic treatises, Aristotle, Strabo, Pliny, and others and implicitly in many more authors.” Writers in antiquity also warned of race mixing and argued that one important explanation for the argued positive characteristics and historical successes of the Greeks, the Romans, and the Germans was that these groups had previously avoided race mixing.<ref>Benjamin Isaac. Collective Degradation: Slavery and the Construction of Race. Proceedings of the Fifth Annual Gilder Lehrman Center International Conference at Yale University. November 7-8, 2003. http://www.yale.edu/glc/events/race/Isaac.pdf</ref><ref name=TNoR/>

Humans must early have realized that at least the physical appearance of the offspring of humans and animals is influenced by the characteristics of the parents. Early agricultural treatises describe selective breeding of animals and plants. Plato's The Republic proposed human eugenic policies based on the selective breeding of animal livestock, which was well-known in ancient Athens. Proposed eugenic policies can also be found in later writings, such as the City of the Sun (1602) by Tommaso Campanella.<ref>Richard Lynn. (2001). Eugenics: A Reassessment. Praeger</ref>

The term race in its early history referred to breeds and lineages. Race was employed, in a related fashion, in several different discourses. In the context of animal husbandry, it was used to describe strains of animals produced through linebreeding. In social discourse, referred to the genealogical lines of noble families along which prized characteristics were thought to pass (e.g., “noblesse de race”). In theological context, it signified lineage, a concept which was employed to explain the transmission of original sin; accordingly, all men inherited the sin of Adam due to being of his race; in the same vein, the descendants of Noah’s sons were referred to as the races of Shem, Ham, and Japheth. Underlying the word usage was a notion of race which involved the idea of genealogy and of the inheritance of traits.<ref name=TNoR/>

However, there was also the Christian creationist position that God had created the different species. These had after their creation by God (a few thousands of years ago) not changed in any fundamental or hereditary way. This made certain theories on race and heredity potentially heretical and dangerous to support.

Early scientific studies

More complete knowledge of different human groups only emerged as European geographic exploration and knowledge expanded. “By the end of the eighteenth century, knowledge of the appearance of various peoples of the world was fairly complete. At this time European scholars began to speculate on these racial differences…”<ref>Brues. Alice M. (1990). People and Races. Waveland Press. p. 19.</ref>

This was also the time when taxonomy started to be studied as a modern science. This among other things demanded reliable measurements. The taxonomies largely relied on morphology (form/structure, comparative anatomy). Morphological characteristics could be easily and reliably measured, unlike physiological, mental, or genetic characteristics, which were difficult or impossible to measure at this time. This reliance on morphology was nothing unique for human taxonomy, but applied to taxonomy in general at this time. Morphological characteristics used in human taxonomy included pigmentation, hair form and skeletal form.

Carl Linnaeus, the founder of modern taxonomy, divided humans into four major subgroups in his Systema Naturae (1735): Homo Europaeus (Europeans), Homo Afer (Sub-Saharan Africans), Homo Asiaticus (Asians), and Homo Americanus (Amerindians). This classification was based on both morphological features and argued differences in temperament and psychology. Generally, it has been argued that Linnaeus's system for classification of organisms, primarily based on morphological differences, has undergone surprisingly little change in the times following it, despite the appearance of genetic measurements. Linnaeus's four subgroups are similar to four of the five major races still described today.<ref name=AH>Andrew Hamilton. Taxonomic Approaches to Races] The Occidental Quarterly. vol. 8, no. 3, Fall 2008 http://toqonline.com/archives/v8n3/TOQv8n3Hamilton.pdf</ref><ref name=TNoR/>

The Australoids were unknown or not well-known until relatively late and were described as a major race by Thomas Huxley in 1870.

Linnaeus in his classification considered only species to have unchanging hereditary characteristics (as created by God). Intra-species groups were considered to be different only due environmental factors and were not called races but “varieties”. Linnaeus himself admitted that this was problematic and used the oxymoronic term “constant varieties” for groups of the same species, which differed despite being exposed to the same environment. This problem continued to be debated. One view was that the existence of human “constant varieties” was evidence for that humans should be divided into different species. This was deemed religiously heretical and considered to be a dangerous idea; it was thought to undermine the moral and spiritual unity of man. Instead, the term race came to be used by individuals who viewed it as a concept different from species and varieties. Initially races were viewed as having acquired hereditary properties through soft inheritance. The whole debate effectively ended when Charles Darwin introduced evolution through natural selection.<ref name=TNoR/>

Confusingly, the term race could also be used to refer to different human groups when they were argued to be different species. This was reflected in questions such as “Are the races of man species?” Race as having a meaning similar to species still occurs today outside of the natural sciences, such as when people refer to the “human race” and mean the “human species” or when referring to fictional “races” such as elves and dwarves.<ref name=TNoR/>

Much of the early research was done within the field of anthropology. One explanation for this is that it was anthropologists who traveled to and made detailed ethnographic studies of different peoples. Such studies also included descriptions of morphological characteristics.

Genetic studies

, Australoids, Caucasoids, East Asians (“Mongoloids”), and Sub-Saharan Africans (“Negroids”).]]
During recent decades, taxonomy in general has been revolutionized by the appearance of increasingly detailed genetic studies. The same has occurred for human taxonomy. This genetic research is today usually not done by anthropologists.

Researchers today often avoid using the politically sensitive word “race” and instead use terms such as “population” in order to avoid accusations of racism.

Both genetic and morphological research have also found support for a general division into three major groups corresponding to certain geographic regions: Western Eurasia and North Africa (in traditional anthropological literature called Caucasoids), Eastern Eurasia (Mongoloids) and Sub-Saharan Africa (Negroids). Oceania (Australoids) och sometimes the Americas (Amerindians) have received similar support. This corresponds to major geographic barriers that made contact between different groups difficult (the Oceans, Sahara, and the Himalayas (and the deserts and the mountain ranges bordering on the Himalayas)).<ref name=TNoR/><ref name=troublesome>Wade, N. (2014). Genes, Race and Human History. Penguin.</ref><ref name=JG>John Goodrum. The Race FAQ. http://web.archive.org/web/20110711111007/http://www.goodrumj.com/RFaqHTML.html</ref>

Regarding agreements and disagreements between classifications, the 2015 peer reviewed book the Genealogy of the Concept and the Biological Construct’s Contemporaneous Utility listed many important historical and recent classifications, and argued that they generally supported the five major races. The book stated that ”all of the classifications include some version of the big three: Caucasoid, Negroid, and Mongoloid – groupings which do not simply reflect continental ancestry. That is, these delineations are not drawn geographically, rather they are drawn biologically. As such, in no instance are North Africans grouped into a “pan-African race” along with Sub-Saharan Africans, and in no instance are South Asians grouped into a “pan-Asian” race along with East Asians.

Secondly, the areas of disagreement are generally sensible in light of the current morphological and genetic data. For example, at times, South Asians were treated as a major biological division separate from other West Eurasians; and it so happens that this is the first major West Eurasian group to separate out at a finer grain of genetic analysis. Likewise, there has been continual disagreement as to the status of Pacific Islanders (these various peoples being classified as a major race separate from the big three, grouped with Mongoloids or at times Australoids, or treated as several major races, etc.); part of the disagreement reflects terminology, much of it reflects discordance between genetic and morphological (e.g., craniometrical) differentiation, and much of it reflects actual biological ambiguity produced by a combination of continual East Asian gene flow into the region and reduced gene flow between subregions.

Other areas of disagreement are likewise biologically sensible. For example, Ethiopians were considered sometimes Caucasoid and sometimes Negroid – and they happen to be rather admixed. The point here is that much of the classificatory confusion parallels actual population complexity. If so, Barbujani and Colonna’s argument is valid: classifications are confused when populations are not well separated or when they are admixed. Yet the classifications show a striking degree of coherence.“<ref name=TNoR/>

Common characteristics of races

This section describes some common characteristics of races used in definitions of race and other general discussion on race.

Current characteristics

Genetic similarity

Amerindians, Italians, Spaniards, Swedes, and three different groups of European Americans (of Western, Central, and Eastern European descent) according to a 2006 study. The Maya Amerindians are clearly distinct from the Europeans.<ref>Seldin MF, Shigeta R, Villoslada P, Selmi C, Tuomilehto J, et al. (2006) European Population Substructure: Clustering of Northern and Southern Populations. PLoS Genet 2(9): e143. doi:10.1371/journal.pgen.0020143 http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.0020143</ref> The Maya Amerindians have been stated to have some European admixture.<ref name=split>Pickrell JK, Pritchard JK (2012) Inference of Population Splits and Mixtures from Genome-Wide Allele Frequency Data. PLoS Genet 8(11): e1002967. doi:10.1371/journal.pgen.1002967 http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002967</ref> This likely means that the difference between Europeans and Amerindians was even larger before this admixture.<br><br>
A diagram of a principal components analysis of global genetic data according to a 2009 study can be found here: External Link.]]
Races consist of genetically similar individuals. Earlier this was assumed to be the case based on characteristics such as phenotypic similarity and common history. Today, this can be directly measured by genetic measurements.

Such genetic similarity is not based on just one or a few “essential” genetic characteristics, but on all as an average or a correlated composite. This means that an individual may differ markedly from the racial average on one or a few genetic characteristics, as long as the individual's genetics despite this overall are similar to the racial average.

Another aspect is that many genetic characteristics correlate with one another. One implication is that it is possible to make increasingly accurate classifications of individuals, when measuring an increasing number of genetic characteristics. Another is that individuals tend to genetically group into different genetic “clusters” that correspond to different races.

Phenotypic similarity

An organism's phenotype is the composite of an organism's observable characteristics or traits, such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior (such as a bird's nest).

A phenotype results from the expression of an organism's genes as well as the influence of environmental factors and the interactions between the two. Organisms with identical genotypes need not necessarily look or act identical because appearance and behavior are modified by environmental and developmental conditions. Likewise, organisms that look alike need not have the same genotype. Regardless, there is often a strong connection between genotype and phenotype, more so for some characteristics than for others.

Races were earlier often categorized primarily by morphological characteristics, which are phenotypic characteristics. Today there is instead a tendency to predominantly focus on genetic characteristics, which are seen as more fundamental and not subject to obscuring environmental factors.

However, the importance of genetic factors needs to be evaluated in relation to phenotypic outcomes. Some genetic variation do not cause any important phenotypic variation, some genetic variation cause small phenotypic variation, and some genotypic variation cause dramatic phenotypic variation.

Finally, much of the practical significance of the race concept is due to the individuals belonging to a particular race having similar phenotypes due to having similar genotypes.

Ethnic similarity

Ethnic characteristics, such as culture, language, and so on, are uncertain markers of genetic similarity that are heavily influenced by environmental factors. Still, in particular ethnicities in early history, and in particular groups such as tribes, may often have had or have similar genetics.

Nested hierarchy of groups

Larger groups can be subdivided into smaller groups. For example, East Asians can be subdivided into groups such as Koreans and Japanese. Various terms have been used for the different levels in this hierarchy, such as “major races”, “geographic races”, or “continental races” for larger groups and “minor races” for smaller groups. At some point in the hierarchy, the term races ceases to be used and may instead be replaced by terms such as peoples, tribes, clans, and villages. Although the term races is rarely used for so small groups, such groups may in principle be races according to many race definitions.

As such, an individual can be genetically similar to and belong to several different but nested groups. For example, an individual can at the same time be both East Asian and Japanese.

An implication of such nested hierarchies is that it possible to count few or many races depending on which level in the hierarchy is examined.
Such nested hierarchies are typical of taxonomies in general, with different species being organized into increasingly larger groups, such as genera and families. Biologists have sometimes disagreed on this species hierarchy and it has been modified as new evidence has been uncovered. The same applies to the racial hierarchy.

Historical characteristics

Races are argued to have some or all of the following historical characteristics, which explain their current genetic similarity.

The members of a race are argued to have similar genetic ancestry. The ancestral genetic relationships between different groups can often be depicted with phylogenetic tree diagrams. Proponents of cladistics argue that such relationships should be the primary basis for taxonomic classifications, at least for species and higher groups.

Studies on the genetic ancestry of groups and studies on the genotypic/phenotypic similarity of groups usually produce similar results. However, there may be certain disagreements, such as birds by genetic ancestry being dinosaurs, but having many dissimilarities with non-bird dinosaurs.

For intra-species groups, the ancestry relationships may be complicated and no longer resemble trees due to interbreeding between different groups within the species. For humans, there have been interbreeding between both ancestral groups (such as Neanderthals) and more anatomically modern humans) and between more recent groups. However, mixed ancestry does not exclude a group from having a similar genetic ancestry - all members of a group may have the same mixed ancestry.

Historical period as an interbreeding population

A race may have had a long historical period as an interbreeding population. This may have caused the group to have become more genetically homogeneous and/or to have become genetically changed by adapting to the local environment.

Historical geographic/cultural barriers to interbreeding with other groups

A race may have had reduced interbreeding with other groups due to geographic and/or cultural barriers. This may have contributed to the race genetically differentiating from other groups.
If there were no such barriers, then there may be no clear, non-arbitrary borders between neighboring groups. Even if so, increasing geographic distance between groups will likely be associated with increasing genetic differences.

Ancestral territory

A race may have had an ancestral territory, where it existed for a period as a breeding population and which may be surrounded to some degree by geographic barriers. This often refers to the geographic areas where the different races lived before recent mass migrations, such as those by Europeans and Sub-Saharan Africans to the Americas.

Ancestral myths, legends, and histories

A race (or at least smaller races and groups such as tribes) may have an ethnic narrative which describes a common ancestral origin of the group and the subsequent history of the group.

Definitions of race

In taxonomy in general, there is disagreement regarding the taxonomic ranks below the species level. Many different terms and definitions have been proposed.<ref>Cronin, Matthew A. (2006) A Proposal to Eliminate Redundant Terminology for Intra-Species Groups. Wildlife Society Bulletin 34 (1):237-241 DOI: 10.2193/0091-7648(2006)34[237:APTERT]2.0.CO;2 http://onlinelibrary.wiley.com/doi/10.2193/0091-7648%282006%2934%5B237:APTERT%5D2.0.CO;2/abstract</ref><ref>Haig SM, Beever EA, Chambers SM, Draheim HM, Dugger BD, Dunham S et al. (2006) Taxonomic considerations in listing subspecies under the U.S. Endangered Species Act. Conserv Biol 20 (6):1584-94. http://dx.doi.org/10.1111/j.1523-1739.2006.00530.x</ref> As such, it is not surprising that there have also been differing definitions of race. They have generally used some combination of the characteristics described above in the section “Common characteristics of races”.

The existence of different definitions have sometimes been used as an argument against the existence of races. However, similar disagreements also exist regarding definitions in taxonomy in general, but this is not seen as proving the non-existence of taxonomic groups and taxonomic hierarchies. That new definitions have been proposed in general and human taxonomy is in part due to better knowledge of group differences.

The Nature of Race: the Genealogy of the Concept and the Biological Construct’s Contemporaneous Utility argued that there is a coherent, operationalizable concept of race which has been remarkably stable across time since it was developed in the 1700s and which underlies and integrates a plethora of local definitions. It argued that ”Underlying the diversities, though, are common conceptual cores. In the case of race, this is the general biological race concept (GBRC). According to this, races are organismic groups which differentiated from one another as a result of historic patterns of filiation; they are groups, which due to histories of sufficient linebreeding, form intraspecific natural divisions, ones which can be identified based on the correlations between the organisms' inherited charactera.“ Furthermore, ”Understood as intraspecific natural divisions, races are divisions of organisms that are sufficiently linebred such that each member is more genetically similar to other members of the same division than to members of other ones but not so linebred that members of different divisions can not readily produce viable offspring“ and ”When lines of descent are sufficiently endogenous, that is, when our extended families are sufficiently linebred, natural division races emerge from artificial. These races have five dimensions, two causal, two essential, and one consequential. Races are the product of extrinsic reproductive barriers and of the historic breeding patterns that these barriers have shaped. They are lines of descent, ones sufficiently linebred to allow for class distinctions, which over the course of generations have accumulated modifications. Owing to their common ancestry, members of a race share phenotypic patterns which can be used to distinguish them from members of other races.“<ref name=TNoR>John Fuerst. (2015). “The Nature of Race: the Genealogy of the Concept and the Biological Construct’s Contemporaneous Utility”. Submitted: December 25, 2014. Published: June 18, 2015. Open Behavioral Genetics. http://openpsych.net/OBG/2015/06/the-nature-of-race/</ref>

Straw men definitions

Critics of the existence of races have often attacked what can be considered straw men definitions of race. One example is by defining biological races so that ”all the members of these races share certain traits and tendencies with each other that they do not share with members of any other race. These traits and tendencies characteristic of a race constitute, on the racialist view, a sort of racial essence“. This straw man definition is then easily refuted by pointing out, for example, that one can find some Blacks who have a higher intelligence than some Whites. However, at least many of the modern definitions imply that the different races differ on average on many different traits, but that individual members may differ widely from this racial average on one or a few characteristics.<ref name=NS/>

Another example could be the existence of albinos with white skin color in all human populations. Again, many of the definitions above state or imply that the different races differ on average on many different traits and that these average differences together characterize a race. An individual may differ greatly from one or a few of the racial averages of a particular race and still be considered a member of this race, if the individual's characteristics despite this overall are similar to those of the race. Thus, a person with albinism would still be considered a member of a race which has on average a very dark skin color, if the person's characteristics overall correspond to those of this race.

Yet another example is that not all Sub-Saharan Africans have the sickle-cell trait and some individuals from outside Sub-Saharan Africa do. Again, non-straw men definitions do not depend on all group members absolutely having or absolutely not having a single (or several) “essentialist” trait(s).

See also the genetic research mentioned in the “Lewontin's fallacy” section in the ”Arguments regarding the existence of races“ article, which support that race is not defined by absolutely having or absolutely not having certain “essentialist” traits, but instead by a very large number of correlated traits.

Critics have argued that these “essentialist” demands are so demanding that they require that the different groups must be separate species or even that they are so demanding that even different species would fail to pass such requirements. ”In practice, the characters that define a species will not be present in all members of that species and absent from all members of other species. Nature is too variable“.<ref name=NS/>

Other straw men definitions or part of such definitions include that each race, as compared to all other races, must be “discrete”, “non-overlapping”, “sharply discontinuous”, etc.<ref name=NS>Neven Sesardic. Race: a social destruction of a biological concept. Biol Philos (2010) 25:143–162 http://dx.doi.org/10.1007/s10539-009-9193-7</ref>

It has also been argued that the views of early race scientists have been incorrectly described as being hardcore essentialist, in order to create a simple “essentialist” straw man definition of race, which can then be easily attacked and defeated. ”It is now clear that individual traits do not make for good differentia. But this is not a new discovery. It was recognized by Buffon, Blumenbach, Darwin, and the many others who argued that one should simultaneously take into account similarity in numerous traits.“<ref name=NS/><ref name=TNoR/>

in pre-colonial populations. It has been used as an argument against the existence of races, with the argument that the different areas do not correspond to the traditional races. Sometimes other maps showing the distribution of other characteristics are used to make similar argument, such as maps showing the distribution of the sickle-cell genetic trait or maps showing the distribution of blood groups. However, such arguments often rely on the “essentialist” straw man definition of race. It is also a straw man in the sense that race realists have not argued that such maps define races.
<br/><br/>
Generally, if only using a few genetic markers (such as only using Y chromosome or mitochondrial haplogroups) or if only sampling a few subgroups in a larger group consisting of many subgroups (such as only sampling a few ethnic groups instead of using a sample representative of the global population), then the results will be varied and arbitrary and may not resemble the results found when using many genetic markers from a representative sample. However, this is not different from any statistical survey/study becoming problematic if using a very small and/or biased sample.
<br/><br/>
See also the section on “Genetic clusters” and “Genetic variation between populations compared to the genetic variation in populations” in the article Arguments regarding the existence of races on racial classification becoming very accurate when using not one, or a few genetic markers, but many.]]
A “modernized” version of the essentialist straw man argument is based on defining race by using mitochondrial or Y-chromosome DNA haplogroups and then pointing out various problems with this. While such haplogroups are useful for certain population studies, they are only a very small part of the human genome and human genetic groups differences, and they are not the racial “essence”.

Arbitrary definitions

Another criticism has been to argue that one can create arbitrary races by picking an arbitrary characteristic and claiming that all persons with this characteristic belong to the same race.
Therefore, the argument is that since European Swedes and African Fulani are both (usually) lactose tolerant, they can (usually) be classified as belonging to a “race” that is defined as consisting of all lactose tolerant persons.

Such arbitrary definitions ignore that race definitions usually include that a race has a similar ancestral origin and they also ignore that at least the modern race definitions do not rely on such single “essentialist” characteristics, but instead on a large number of correlated characteristics.

Non-straw men race "essences"

There are arguably some senses in which different races do have different racial “essences” (but not in the sense(s) used in straw men definitions).

First, the members of a race are argued to share a particular genetic ancestry as described above (not necessarily a monophyletic genetic ancestry). This is an “essence” characteristic shared by all race members and not shared by any race non-members.

Second, as described in Arguments regarding the existence of races: Genetic clusters, it is possible to genetically compare different individuals based on how overall genetically similar or dissimilar they are. This can be visualized as it being possible to determine an individual's location in a multi-dimensional genetic “space”, with the dimensions consisting of all the genetic variables that vary between individuals. If using an increasing number of genetic markers, then an individual's location in this genetic space can be increasingly accurately determined. If using the entire genome of an individual, then an individual's location in this genetic space can in principle be determined perfectly. “Clusters” of genetically similar individuals in this genetic space very often correspond to races that share a particular genetic ancestry as described above. Therefore, the genetic space can often be naturally divided into different subspaces that correspond to different genetic clusters/races. Then belonging to a particular genetic subspace is again an “essence” characteristic shared by all race members and not shared by any race non-members.

In some cases, it may be less clear and natural how to exactly define the genetic ancestry requirements for belonging to a particular genetic ancestry group and correspondingly how exactly to draw the boundary between different genetic subspaces. However, once this is decided (even if this decision is to some degree arbitrary), then this decision delimits groups that have “essences” in the form of all members having a shared genetic ancestry and belonging to a particular genetic subspace, characteristics not shared by any non-members.

Other terms

Subspecies

Landraces and breeds

A landrace is a variety of a domesticated species of animal or plant that has not been developed through selective breeding. A breed is a variety of a domesticated animal that has been developed through selective breeding.

Fictional races

Fantasy/Science fiction often describe various fictional groups of intelligent beings as “races”. This despite that such groups may be from different planets and likely would fall outside the whole current taxonomic system if existing in reality. Regardless, this common usage may create confusion regarding race.

Many populations are to some degree racially mixed. This raises the question of how such groups should be classified. In general, there are three main cases:

The degree of admixture is small and recent, such as the small European admixture in African Americans. Such groups have generally by race realist scientists been treated as belonging to the race that is predominant in their ancestry (Sub-Saharan Africans in the case of African Americans). However, the admixture may be important if making a more detailed analysis. For example, the European admixture in African Americans is argued to have caused a somewhat higher average genotypic IQ in African Americans than in the Sub-Saharan Africans living in Africa.<ref name=RDII>Richard Lynn. Race differences in Intelligence. 2006. Washington Summit Publishers.</ref> There have been classifications, such as the one-drop rule, which contradict this, but these can be seen as politically motivated rather than scientifically based.

The admixture in the group is large, recent, and may be heterogeneous. Thus, the group may have ancestry from several different races and in various combinations and to varying degrees. Such groups have by race realist scientists generally been classified as not being a race and simply being a “mixed race” groups, a “hybrid” group, etc. A similar situation exists in taxonomy in general, where it is accepted that some individuals (such as those in border zones between recognized subspecies) do not belong to any of the recognized subspecies. This also invalidates a common race denialist tactic, which consists of pointing out various problems with such groups being races - these groups are in fact not races.

:Society at large and individuals belonging to such groups may not follow this classification. For example, some mulattoes may prefer to classify themselves as Africans. Regardless, it is today possible to genetically test and objectively determine the racial make-up of a person or a group.

The admixture occurred in the distant past. Typically, there was race mixing, but it occurred a long time ago, there has been much interbreeding in the group causing it to become genetically homogeneous, and the long time period has caused the group to have become adapted to the local environment through natural selection. Such a group may best be described as a (new) race. In fact, almost all or all human races belong to this group, since in the distant past there have been some interbreeding with groups such as Neanderthals, Denisovans and archaic human groups in Africa.<ref>Alves I, Šrámková Hanulová A, Foll M, Excoffier L (2012) Genomic Data Reveal a Complex Making of Humans. PLoS Genet 8(7): e1002837. doi:10.1371/journal.pgen.1002837 http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002837</ref><ref>Hammer, M.F.; Woerner, A.E.; Mendez, F.L.; Watkins, J.C.; Wall, J.D. (2011). “Genetic evidence for archaic admixture in Africa”. Proceedings of the National Academy of Sciences 108 (37): 15123–15128. doi:10.1073/pnas.1109300108 http://www.pnas.org/content/108/37/15123.full</ref><ref>Evolutionary History and Adaptation from High-Coverage Whole-Genome Sequences of Diverse African Hunter-Gatherers. Joseph Lachance, Benjamin Vernot, Clara C. Elbers, Bart Ferwerda, Alain Froment, Jean-Marie Bodo, Godfrey Lema, Wenqing Fu, Thomas B. Nyambo, Timothy R. Rebbeck, Kun Zhang, Joshua M. Akey, Sarah A. Tishkoff. Cell - 3 August 2012 (Vol. 150, Issue 3, pp. 457-469) http://www.cell.com/abstract/S0092-8674%2812%2900831-8</ref> Another example is the interbreeding between agriculturalists and hunger-gatherers in Europe that occurred many thousands of years ago. These agriculturalists have sometimes been described as being from the “Middle East”, but they most likely were quite different from the current populations in the Middle East, and the very slow journey most likely cause large evolutionary changes even before they arrived at their final destination, where natural selection caused further evolutionary changes.

Another view is that the status of a group as race or a mixed-race group depends on context. ”the divisions identified depend on the meta-population under consideration. From the perspective of natural history and zoology, the meta-population would be the global one (at a certain time) since of concern is the natural history of the species as a whole. This is how most people understand the concept. However, one need not look at the global population and thus one can speak of groups locally racially differentiated with respect to each other. The upshot is that “mixed races” on the global level can be “full races” on the local one. Mestizos and Mulattos in Mexico represent two “mixed” races from the perspective of the global meta-population. From the perspective of the Mexican meta-population, they likely represent two different “full” races.“<ref name=TNoR/>

Race differences

Numerous differences between racial groups have been described in scientific studies. In some cases this only refers to measured phenotypic differences, but there is also a rapidly increasing number of studies describing genotypic differences.

Arguments regarding the existence of races

The existence of human races was almost universally accepted by scientists before the middle of the twentieth century. Thereafter, it has become increasingly politically incorrect to support the existence of human races. Despite this, many scientists still support the existence of human races. See the article Arguments regarding the existence of races for a further discussion.

Race is a concept which classifies human beings according to broad physical characteristics such as skin color. Many assert that race is more than physical and claim that different races have different psychological, intellectual and religious characteristics.

Various different classifications have been proposed for human races in the past. Evolutionary textbooks used to have a chapter on eugenics that discussed various “races”, such as Negroid (mostly Africans), Mongoloid (mostly Asian) and Caucasian (mostly Europeans) and which of the races were the furthest along in evolution.<ref>For example, Hunter, George William, A Civic Biology (1914), p.196: “At the present time, there exists upon the Earth five races or varieties of man, each very different from the other in instincts, social customs, and, to an extent, in structure. These are the Ethiopian or negro type, originating in Africa; the Malay or brown race, from the islands of the Pacific; the American Indian; the Mongolian or yellow race, including the natives of China, Japan, and the Eskimos, and finally the highest type of all, the Caucasians, represented by the civilized white inhabitants of Europe and America.”</ref>

The concept of race is no longer considered scientifically valid, as there is little genetic difference between the so-called races, and those differences are mostly superficial. Distinguishing humans on the basis of minor differences or not on the original basis of the theory, humans are either one race or several thousand. The most obvious example of difference between races is the fact that while black and pacific-islander people are, obviously, black, all people have the same type of skin-coloring pigment (melanin), each race's skin color being dependent on the melanin content of the skin.

Despite its questionable validity, race is still detailed in government census and other forms, mostly for convenience in classifying individuals into groups.

The belief that one race is inherently better or worse than others is known as racism. For historical accuracy it's worth noting that until the events of the 1960s holders of racist beliefs were termed 'racialists' rather than the modern term, 'racists'.

Human geographers today prefer to discuss people in terms of ethnicities rather than races; the principal difference between one's ethnicity and one's race is that race is superficial while ethnicity carries with it a whole host of cultural traditions. For example, the Anglo-Saxons of the British isles have cultural traditions that are distinct from the ethnic inhabitants of Germany's Rhineland, though both ethnic groups would be considered racially caucasian.